(i) Field of the Invention
The present invention relates to an optical information storage apparatus which irradiates an optical information storage medium with light to access the optical information storage medium, and to an optical device for use in the optical information storage apparatus.
(ii) Description of the Related Art
With enhancement of a computer performance in recent years, a large-capacity storage apparatus for a computer has been demanded, and a hard disk apparatus has been noted as a candidate for the storage apparatus, and an optical information storage apparatus represented by a magnetic optical disk apparatus using a magnetic optical disk as an optical information storage medium has also been noted. Particularly, the optical information storage apparatus is regarded as most important because the optical information storage medium is provided with characteristics such as replaceability, large capacity, and small size and light weight.
In order to turn the optical information storage apparatus to practical use as a computer storage apparatus, and the like, the price reduction of the apparatus is necessary, and particularly the price reduction of an optical head for irradiating the optical information storage medium with light among the elements of the optical information storage apparatus has strongly be demanded. Moreover, as a countermeasure for the price reduction of the optical head, it is proposed that the reduction in size and weight of the optical head and the reduction of the number of adjustment processes should be realized by decreasing the number of optical head components.
However, in the conventional proposals for a component number decreasing system, there are problems that the optical head and optical information storage apparatus cannot sufficiently be miniaturized or lightened, and that the quantity of light to be radiated to the optical information storage medium decreases and the light quantity falls short during writing.